Smoothing technology-based blind authentication method and system for frequency selective fading channel

ABSTRACT

Disclosed is a blind authentication method for a frequency selective fading channel based on a smoothing technique. The method includes: transmitting carrier signals to a frequency selective fading channel having multiple paths, where each carrier signal includes an authentication signal, a pilot signal and an information signal, receiving the carrier signals, performing BKIC processing on a carrier signal in each path to obtain a target signal, and performing differential signal processing on the target signal to obtain a target authentication signal, obtaining a reference signal based on a key and the pilot signal in the each path, performing the differential signal processing on the reference signal to obtain a reference authentication signal, and calculating a correlation between the target authentication signal and the reference authentication signal to obtain a test statistic; and comparing the test statistic with a prescribed threshold to determine whether the carrier signal in the each of the plurality of paths can pass authentication.

TECHNICAL FIELD

The present disclosure relates to the field of wireless communicationtechnologies, and in particular to a blind authentication method andsystem for a frequency selective fading channel based on a smoothingtechnique.

BACKGROUND

At present, three main physical layer authentication technologies exist.The first authentication technology is the Spread SpectrumAuthentication method (Auth-SS). The basic idea is to use thetraditional direct-sequence spread spectrum or frequency modulationtechnology. Since different pulses use different frequencies, thistechnology requires a certain amount of bandwidth to achieveauthentication. In addition, a key limitation of the Auth-SS technologyis that only users who understand prior knowledge of the spread spectrumtechnology are involved in the communication. Therefore, the scope ofapplication of this technology is relatively narrow.

The second authentication technology is based on the Authentication withTime Division Multiplexing) (Auth-TDM). The basic idea is that thetransmitter periodically sends information signals and authenticationsignals alternately. After receiving a signal, the receiver directlyextracts the desired authentication information to implementauthentication of the signal. The Auth-TDM is an authenticationtechnology proposed in the early development of wireless communication.The advantage is that it is easy to operate, and that authenticationsignals and information do not need to be pre-processed (encryption maybe performed for security reasons) before signals are transmitted. Theauthentication signal is transmitted independently of the informationsignal, so the authentication signal needs to occupy a certain amount ofbandwidth. With the increasing amount of wireless information, furtherimprovement of information privacy for users and the continuousenhancement of attack technologies of the enemy, the security of thisauthentication technology is greatly challenged and cannot meet therequirements of users.

The third authentication technology is the Authentication withSuperimposition (Auth-SUP). The basic idea is to superimpose theauthentication signal on the information signal (the superimpositionmanner may be arbitrary and is determined by the key), and then thetransmitter simultaneously transmits the authentication signal and theinformation signal, and after the receiver receives the signals, theauthentication signal in the superimposed signals is extracted by usingthe key to achieve the purpose of signal authentication.

Compared with the early Auth-TDM technology, in the Auth-SUPauthentication technology, the authentication signal and the informationsignal need to be processed before signal transmission, a certain signalprocessing capacity of the transmitter is required, which is morecomplicated to achieve than the Auth-TDM technology, and theauthentication signal and the information signal are simultaneouslysent, so that extra bandwidth is not occupied. At this time, since theauthentication signal is superimposed in the information signal, thereceiver needs to extract the information after receiving the signal, sothe signal processing difficulty is higher than that of the Auth-TDMtechnology, but the concealment of the authentication information ishigher than that of the Auth-TDM. In addition, since the authenticationsignal plays a role of noise for the extraction of the informationsignal, the signal-to-noise ratio (SNR) of the receiver iscorrespondingly reduced, which adversely affects the extraction of theinformation signal.

In the existing Auth-TDM and Auth-SUP authentication technologies,another pilot signal is further transmitted in addition to theinformation signal and the authentication signal since for the twoauthentication technologies, the receiver needs to estimate the channelparameters and recover the symbols after receiving the signals and thenextracts the authentication signal, so that a certain signal processingcapability of the receiver is also required. In some specific cases,these signal processing technologies may not be feasible and may easilycause estimation errors in the channel parameter estimation and symbolrecovery processes, which may adversely affect the final extraction ofthe authentication signal.

In addition, the Auth-TDM, the Auth-SS, and the Auth-SUP expose the factthat authentication information is included. Auth-SS and Auth-TDMtechnologies are more likely to attract the attention of other users inthe scenario, especially hostile users, compared with conventionalsignals that do not include authentication information. The hostile useranalyzes, counterfeits or tampers with the signal, and the legitimatereceiver cannot authenticate the expected signal. Relatively speaking,the concealment of the Auth-SUP authentication technology issignificantly higher than that of Auth-SS and Auth-TDM. However, thissuperiority is based on the premise that the computing power of thehostile user is limited. Once the computing power of the hostile user isincreased, it is also possible for the hostile user to extract or evendestroy the authentication information.

It must be mentioned that the existing Auth-SS technology and Auth-SUPtechnology have a severe performance degradation in the frequencyselective fading channel scenario. The reality is that as the number ofwireless communication users continues to increase, the communicationenvironment will become more complex and the possibility of interferencewill increase. As the number of urban communication users increases andthe city continues to develop, the simple time invariant fading channelor the simple time-varying fading channel is not sufficient tocharacterize the current communication environment. In particular, dueto the blocking of urban buildings, multipath fading becomes normal.Therefore, it is necessary to consider the wireless communicationphysical layer authentication technology based on the frequencyselective fading channel to improve the security of wirelesscommunication and meet the communication security requirements of users.

SUMMARY

In view of the above, the present disclosure aims to provide a blindauthentication method and system for a frequency selective fadingchannel based on a smoothing technique. In the method, device andsystem, extra signal bandwidth is not needed, the authentication signaldoes not become noise affecting the extraction of an information signalin a carrier signal, and the statistical characteristic of the noise atthe receiver is not affected.

Thus, in a first aspect of the present disclosure, a blindauthentication method for a frequency selective fading channel based ona smoothing technique is provided, and is a physical layerauthentication method for wireless communication of a wirelesscommunication system having a transmitter and a receiver. The methodincludes: transmitting, by the transmitter, carrier signals to awireless channel, where each of the carrier signals includes anauthentication signal, a pilot signal, and an information signal, theauthentication signal is superimposed on the pilot signal, and thewireless channel is a frequency selective fading channel with aplurality of paths; receiving, by the receiver, the carrier signals,performing blind known interference cancellation (BKIC) processing on acarrier signal in each of the plurality of paths of the frequencyselective fading channel to obtain a target signal, and performingdifferential signal processing on the target signal to obtain a targetauthentication signal, where in the BKIC processing, a pilot signal inthe each of the plurality of paths is cancelled through a smoothingtechnique by using adjacent symbols; obtaining, by the receiver, areference authentication signal based on a key and the pilot signal inthe each of the plurality of paths, and calculating a correlationbetween the target authentication signal and the referenceauthentication signal to obtain a test statistic; and determiningwhether the test statistic is not less than a prescribed threshold todetermine whether the carrier signal in the each of the plurality ofpaths is capable of passing authentication.

In the present disclosure, the authentication signal is superimposed onthe pilot signal. Thus, the Signal to Interference plus Noise Ratio atthe receiver may not be affected. In the BKIC processing, the pilotsignal is cancelled through the smoothing technique by using theadjacent symbols. In this case, the pilot signal can be cancelledthrough the smoothing technique without channel estimation.

In the blind authentication method provided in the first aspect of thepresent disclosure, the carrier signal is transmitted in blocks in aform of data blocks to facilitate operation of data.

In the blind authentication method provided in the first aspect of thepresent disclosure, in each block of the carrier signal, a sum of alength of a pilot signal and a length of an information signal is equalto a length of each carrier signal.

In addition, in the blind authentication method provided in the firstaspect of the present disclosure, the reference signal is obtained basedon the key and the pilot signal by using a hash matrix. Thus, thereference signal is processed to obtain the reference authenticationsignal and it can be determined whether the target authentication signalpasses the authentication according to the correlation between thereference authentication signal and the target authentication signal.

In the blind authentication method provided in the first aspect of thepresent disclosure, if the test statistic is not less than theprescribed threshold, the carrier signal passes the authentication.

In the blind authentication method provided in the first aspect of thepresent disclosure, the prescribed threshold is obtained based on astatistical characteristic of the pilot signal and a preset upper limitof a false alarm probability.

In a second aspect of the present disclosure, a blind authenticationdevice for a frequency selective fading channel based on a smoothingtechnique is provided. The device includes a processor and a memory. Theprocessor is configured to execute a computer program stored in thememory to implement any physical layer blind authentication methoddescribed above.

In a third aspect of the present disclosure, a computer readable storagemedium is provided and is configured to store at least one instructionwhich, when executed by a processor, implements any blind authenticationmethod described above.

In a fourth aspect of the present disclosure, a blind authenticationsystem for a frequency selective fading channel based on a smoothingtechnique is provided. The system includes a transmitting device and areceiving device. The transmitting device is configured to transmitcarrier signals to a wireless channel, where each of the carrier signalsincludes an authentication signal, a pilot signal and an informationsignal, the authentication signal is superimposed on the pilot signal,and the wireless channel is a frequency selective fading channel havinga plurality of paths. The receiving device includes: a first processingmodule, a second processing module and a determining module. The firstprocessing module is configured to receive the carrier signals, performblind known interference cancellation (BKIC) processing on a carriersignal in each of the plurality of paths of the frequency selectivefading channel to obtain a target signal, and perform differentialsignal processing on the target signal to obtain a target authenticationsignal, where in the BKIC processing, a pilot signal in the each of theplurality of paths is cancelled through a smoothing technique by usingadjacent symbols. The second processing module is configured to obtain areference signal based on a key and the pilot signal in the each of theplurality of paths, perform the differential signal processing on thereference signal to obtain a reference authentication signal, andcalculate a correlation between the target authentication signal and thereference authentication signal subjected to the differential signalprocessing to obtain a test statistic. The determining module isconfigured to compare the test statistic with a prescribed threshold todetermine whether the carrier signal in the each of the plurality ofpaths is capable of passing authentication.

In the present disclosure, the transmitting device of the blindauthentication system superimposes the authentication signal on thepilot signal. Thus, no extra transmitting bandwidth resource isoccupied. The receiving device of the blind authentication systemperforms BKIC processing in which the pilot signal is cancelled throughthe smoothing technique by using the adjacent symbols. In this case, thereceiving device can cancel the pilot signal through the smoothingtechnique without channel estimation.

In the blind authentication system provided in the fourth aspect of thepresent disclosure, the second processing module is configured to obtainthe reference signal based on the key and the pilot signal using thehash matrix. Thus, the reference signal is processed to obtain thereference authentication signal and it can be determined whether thetarget authentication signal passes the authentication according to thecorrelation between the reference authentication signal and the targetauthentication signal.

In the blind authentication system provided in the fourth aspect of thepresent disclosure, in the determining module, the prescribed thresholdis obtained based on a statistical characteristic of the pilot signaland a preset upper limit of a false alarm probability.

Compared with the existing art, the embodiments of the presentdisclosure have the beneficial effects below.

Compared with the existing Auth-SS, Auth-SUP, and Auth-TDM, the presentdisclosure requires no extra signal bandwidth to implementauthentication of the physical layer of the wireless communication, theauthentication signal does not become noise affecting extraction of thereceiving signal, and the statistical characteristics of noise at thereceiver is not affected. The blind authentication technology providedby the present disclosure deals with a frequency selective fadingchannel, and is more applicable to complicated and variable wirelesscommunication environment in the actual communication scenarios. Inaddition, since in the present disclosure, the authentication signal issuperimposed on the pilot signal, if the entire signal obtained bysuperimposing the authentication signal and the pilot is used as a pilotsignal, the accuracy of channel estimation can further be improved.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a schematic diagram illustrating signal transmission of aphysical layer blind authentication method according to an embodiment ofthe present disclosure.

FIG. 2 is a schematic flowchart of a physical layer blind authenticationmethod according to an embodiment of the present disclosure.

FIG. 3 is a schematic structural diagram of a signal transmitted by atransmitter in a physical layer blind authentication method according toan embodiment of the present disclosure.

FIG. 4 is a schematic flowchart of a process of blind known interferencecancellation (BKIC) processing at a receiver in a physical layer blindauthentication method according to an embodiment of the presentdisclosure.

FIG. 5 is a schematic diagram illustrating signal processing modules ofa transmitter in a physical layer blind authentication system accordingto an embodiment of the present disclosure.

FIG. 6 is a schematic diagram illustrating signal processing modules ofa receiver in a physical layer blind authentication system according toan embodiment of the present disclosure.

FIG. 7 is a schematic structural diagram of a physical layer blindauthentication device according to an embodiment of the presentdisclosure.

DETAILED DESCRIPTION

The preferred embodiments of the present disclosure will be described indetail below with reference to the drawings. In the followingdescription, the same components are denoted by the same referencenumerals, and the description thereof will not be repeated. In addition,the drawings are merely schematic and the ratio of the dimensions of thecomponents to each other or the shapes of the components and the likemay be different from the actual ones.

It should be noted that the terms “first”, “second”, “third”, “fourth”and the like in the description, claims and above drawings of thepresent disclosure are used to distinguish between different objects,and are not intended to describe a specific order. Furthermore, theterms “comprises” and “comprising” and any variant thereof are intendedto cover a non-exclusive inclusion. For example, a process, method,system, product, or device that includes a series of steps or units isnot limited to the listed steps or units, but optionally also includessteps or units not listed, or other steps or units optionally inherentto these processes, methods, products or devices.

The embodiments disclose a blind authentication method, device andsystem for a frequency selective fading channel based on a smoothingtechnique, is a physical layer authentication method, device and systemfor wireless communication of a wireless communication system having atransmitter and a receiver. That is, the embodiments disclose a physicallayer blind authentication method, device, and system for a wirelesscommunication frequency selective fading channel based on a smoothingtechnique. The physical layer authentication can be performed moreaccurately. The details are described below in conjunction with thedrawings.

FIG. 1 is a schematic diagram illustrating signal transmission of aphysical layer blind authentication method according to an embodiment ofthe present disclosure.

In the present embodiment, as shown in FIG. 1, the physical layer blindauthentication method for the wireless communication frequency selectivefading channel based on the smoothing technique is based on a generalsignal transmission model. In this signal transmission model, four usersare included, the sending party (transmitter) is a legitimate sendingparty, the transmitter transmits a signal to the legitimate receivingparty (the receiver), and the other two receiving parties are alistening user and a hostile user in the system. Once the hostile userfinds that authentication information may exist in the signal sent bythe transmitter, the hostile user will analyze the signal, and attemptto extract, destroy, or even tamper with the authentication information.However, the embodiment is not limited thereto, two or more transmittersmay exist, two or more legitimate receiving parties may exist, and twoor more listening users and two or more hostile users may exist.

In the present embodiment, it is assumed that the transmitter and thereceiver jointly have a key for authentication, so that the receiver canuse the key to extract authentication information from the signaltransmitted by the transmitter. The authentication signal includesauthentication information. In the present embodiment, the carriersignal includes an authentication signal, and the conventional signaldoes not include an authentication signal. The listening user knowsnothing about the authentication method. Although the listening user canaccept and recover the signal sent by the transmitter, the listeninguser does not analyze the signal in depth and does not affect theauthentication process. The hostile user can detect the existence of theauthentication signal by analyzing the characteristics of the signal,and intends to destroy the authentication signal.

In the present embodiment, the transmitter in the above signal model mayinclude a base station or a user equipment. The base station (e.g., anaccess point) may refer to a device in an access network thatcommunicates with a wireless terminal over one or more sectors over anair interface. The base station may be used to convert the received airframe and the IP packet to each other and act as a router between thewireless terminal and the rest of the access network, where the rest ofthe access network may include an Internet Protocol (IP) network. Thebase station may also coordinate attribute management of the airinterface. For example, the base station may be a Base TransceiverStation (BTS) in Global System for Mobile Communication (GSM) or CodeDivision Multiple Access (CDMA), or may be a base station (NodeB) inwideband CDMA (WCDMA), or may be an evolutional Node B (NodeB or eNB ore-NodeB) in Long-Term Evolution (LTE), which is not limited in thepresent embodiment.

The user equipment may include, but is not limited to, a smart phone, anotebook computer, a personal computer (PC), a personal digitalassistant (PDA), a mobile Internet device (MID), a wearable device (suchas a smart watch, a smart bracelet and smart glasses) and various typesof electronic devices, where the operating system of the user equipmentmay include, but is not limited to, an Android operating system, an IOSoperating system, a Symbian operating system, a Black Berry operatingsystem, the Windows Phone 8 operating system and so on, which is notlimited in the present embodiment.

In the present embodiment, the transmitter in the above signal modeltransmits a signal to the receiver through the wireless channel, wherethe receiver may include the base station. The base station (e.g., anaccess point) may refer to a device in an access network thatcommunicates with a wireless terminal over one or more sectors over anair interface. The base station may be used to convert the received airframe and the IP packet to each other and act as a router between thewireless terminal and the rest of the access network, where the rest ofthe access network may include an Internet Protocol (IP) network. Thebase station may also coordinate attribute management of the airinterface. For example, the base station may be a Base TransceiverStation (BTS) in GSM or CDMA, or may be a base station (NodeB) in WCDMA,or may be an evolutional Node B (NodeB or eNB or e-NodeB) in LTE, whichis not limited in the present embodiment.

The receiver may further include a user equipment. The user equipmentmay include, but is not limited to, a smart phone, a notebook computer,a personal computer (PC), a personal digital assistant (PDA), a mobileInternet device (MID), a wearable device (such as a smart watch, a smartbracelet and smart glasses) and various types of electronic devices,where the operating system of the user equipment may include, but is notlimited to, an Android operating system, an IOS operating system, aSymbian operating system, a Black Berry operating system, the WindowsPhone 8 operating system and so on, which is not limited in the presentembodiment.

The embodiments disclose a physical layer blind authentication methodfor a wireless communication frequency selective fading channel based ona smoothing technique. FIG. 2 is a schematic flowchart of a physicallayer blind authentication method according to an embodiment of thepresent disclosure. FIG. 3 is a schematic structural diagram of a signaltransmitted by a transmitter in a physical layer blind authenticationmethod according to an embodiment of the present disclosure.

In the present embodiment, the physical layer blind authenticationmethod of the wireless communication frequency selective fading channelbased on the smoothing technique is a physical layer authenticationmethod for wireless communication of the wireless communication systemhaving the transmitter and the receiver. Based on the signaltransmission model described above, as shown in FIG. 2, the transmittertransmits carrier signals to the wireless channel. A carrier signalincludes an authentication signal, a pilot signal, and an informationsignal. The authentication signal is superimposed on the pilot signal.The wireless channel is a frequency selective fading channel withmultiple paths (step S101).

In step S101, as shown in FIG. 3, the carrier signal includes anauthentication signal, a pilot signal, and an information signal, andthe authentication signal is superimposed on the pilot signal. Thesignal length of the authentication signal is equal to the signal lengthof the pilot signal. Thus, the superimposition of the authenticationsignal onto the pilot signal avoids taking up extra signal bandwidth.

In the present embodiment, the information signal includes informationto be transmitted by the user at the transmitter. The carrier signaltransmitted by the transmitter is transmitted in blocks in the form ofdata blocks. Each block of the carrier signal includes a pilot portionand an information portion. The pilot portion includes an authenticationsignal and a pilot signal. The information portion includes aninformation signal. In addition, the carrier signal is transmitted inblocks in the form of data blocks, which facilitates manipulation of thedata.

In the present embodiment, the signal length of the authenticationsignal or the pilot signal is the first length, the signal length of theinformation signal is the second length, the length of each block of thecarrier signal is the total length, and the sum of the signal length ofthe authentication signal or the pilot signal and the signal length ofthe information signal is equal to the length of each block of thecarrier signal, that is, the sum of the first length and the secondlength is equal to the total length.

In the present embodiment, the authentication signal is obtained throughthe pilot signal and the key, that is, the authentication signal isobtained through the pilot signal and the key using the hash matrix. Theobtained authentication signal is superimposed on the pilot signal, andthe pilot portion of each block of the carrier signal is obtained. Thesignal expression of the pilot portion is described below.

m _(i)=ρ_(s) p _(i)+ρ_(t) t _(i)  (1)

In the above signal formula (1) of the pilot portion, ρ_(s) ² and ρ_(t)² are the power allocation factors of the pilot information and theauthentication signal. Assuming that the authentication signal and thepilot signal are independent of each other, E{p_(i) ^(H)t_(i)}=0 isobtained.

In the present embodiment, the signal of the pilot portion and theinformation signal of the information portion are combined to form eachblock of the carrier signal.

Further, in the present embodiment, the transmission channel of thecarrier signal is a wireless channel and is a frequency selective fadingchannel. The frequency selective fading channel has multiple paths, thatis, the frequency selective fading channel is a multipath channel. Theexpression of a carrier signal that has passed through the frequencyselective fading channel is described below.

y _(iL+k) =h _(iL+k) x _(iL+k) x _(iL+k) +n _(iL+k)  (2)

In the present embodiment, the channel response h_(iL+k) of thefrequency selective fading channel follows a complex Gaussiandistribution with a mean of zero and a variance of σ_(h) ².n_(iL+k)˜CN(0,σ_(n) ²) is the noise at the receiver, and follows aGaussian random variable with a mean of zero and a variance of σ_(n) ².

In the present embodiment, in the channel response, ω_(iL+k)˜CN(0,σ_(ω)²) is dynamic noise, and σ_(ω) ²=(1−a²)σ_(h) ². In general, a is thefading correlation coefficient of the frequency selective fadingchannel, and is determined by the channel Doppler spread and thetransmitting bandwidth. In particular, a small value of a indicates fastfading, and a large value of a indicates slow fading. In many types ofscenarios, the value of a is available at the receiver. In the actualwireless system scenario, the value of a ranges in a very smallinterval, such as a∈[0.9,1].

In the present embodiment, the physical layer blind authenticationmethod further includes receiving, by the receiver, the carrier signals,performing blind known interference cancellation (BKIC) processing onthe carrier signal in each path of the frequency selective fadingchannel to obtain a target signal. In the BKIC processing, the pilotsignal is cancelled through the smoothing technique by using adjacentsymbols (step S102).

In the present embodiment, the receiver receives the carrier signals. Acarrier signal includes a pilot portion and an information portion. Thephysical layer blind authentication method according to the presentembodiment is mainly used for processing the pilot portion of thecarrier signal at the receiver. The expression of the pilot portion ofthe carrier signal received at the receiver is described below.

y _(k)=ρ_(d=0) ^(D) ^(max) h _(k,d)(ρ_(s) p _(k−d)+ρ_(t) t _(k−d))+n_(k) , iL≤k≤iL+L ₁  (3)

In the present embodiment, the wireless channel is a frequency selectivefading channel. A frequency selective fading channel has multiple paths.D_(max) is information about the maximum delay in the multiple paths,and is usually known in broadband wireless communication systems. Forexample, in an Orthogonal Frequency Division Multiplexing (OFDM) system,the predefined cyclic prefix determines the maximum delay in all paths.

In the present embodiment, the following processing for the carriersignal refers to the processing for the pilot portion of the carriersignal.

In the present embodiment, a blind authentication technique is used oneach potential path of the frequency selective fading channel.Specifically, first, blind known interference cancellation (BKIC)processing may be performed on the carrier signal in the first path ofthe frequency selective fading channel, and then the same blind knowninterference cancellation (BKIC) processing method may be similarly usedto remove the pilot signal in the carrier signal in the second path ofthe frequency selective fading channel, the above-mentioned blind knowninterference cancellation (BKIC) process is repeated (D_(max)+1) times,so that the pilot signal in the carrier signal in each path of thefrequency selective fading channel is cancelled. That is, blind knowninterference cancellation (BKIC) processing is performed on the carriersignal in each path of the frequency selective fading channel insequence.

In step S102, the receiver receives the carrier signals, and performsblind known interference cancellation (BKIC) processing on the carriersignal in each path of the frequency selective fading channel to obtainthe target signal. The blind known interference cancellation (BKIC)processing is to use adjacent symbols to cancel the pilot signal in thecarrier signal through the smoothing technique. Usually, the channelsituation needs to be estimated for cancelling the pilot signal in thecarrier signal. If the channel responds that effective estimation cannotbe performed, the pilot signal in the carrier signal is difficult tocancel. With the blind known interference cancellation method, the pilotsignal can be cancelled while the estimation of the channel is avoided.

In the present embodiment, the carrier signal received by the receivermay or may not include the authentication signal. That the carriersignal includes the authentication information is set as a firstcondition, and that the carrier signal does not include theauthentication signal is set as a second condition.

FIG. 4 is a schematic flowchart of a process of blind known interferencecancellation (BKIC) processing at the receiver in the physical layerblind authentication method according to an embodiment of the presentdisclosure.

In the present embodiment, as shown in FIG. 4, the method of cancelingthe pilot signal in the carrier signal is the same on each path of thefrequency selective fading channel. Specifically, the pilot signal inthe carrier signal on each path of the frequency selective fadingchannel is cancelled by using the BKIC processing method. The BKICprocessing method includes determining an expression of each symbolunder different conditions (step S401) and estimating the target signalusing the expression of the symbol (step S402).

In step S401, an expression of each symbol under different conditions isdetermined.

Under the first condition, the expression of each symbol is describedbelow.

$\begin{matrix}{{{b_{k}H_{1}} = {{y_{k} - {\frac{P_{k}}{a\; P_{k + 1}}y_{k + 1}}} = {{h_{k}\rho_{t}t_{k}} + n_{k} - {\frac{P_{k}}{a\; P_{k + 1}}\left( {{h_{k + 1}\rho_{t}t_{k + 1}} + n_{k + 1}} \right)} - \frac{\omega_{k + 1}\rho_{s}P_{k}}{a}}}}\mspace{20mu} {k \in \left\{ {1,2,\ldots \mspace{14mu},\ {L_{1} - 1}} \right\}}} & (4)\end{matrix}$

Under the second condition, the expression of each symbol is describedbelow.

$\begin{matrix}{{b_{k}H_{0}} = {n_{k} - {\frac{P_{k}}{a\; P_{k + 1}}n_{k + 1}} + \frac{\omega_{k + 1}P_{k}}{a}}} & (5)\end{matrix}$

It can be seen from the above formula that correlation noise existsbetween adjacent symbols, and the correlation noise in the formula (4)cannot be corrected by the ordinary noise whitening technique, and thecorrelation noise needs to be cancelled through step S402, andh_(k)ρ_(t)t_(k)+n_(k) is estimated.

In step S402, the target signal is estimated using the expression of thesymbol. The above formula (4) is expressed described below.

$\begin{matrix}{\mspace{79mu} {u_{1} = {b_{1} = {{h_{1}\rho_{t}t_{1}} + n_{1} - {\frac{p_{1}}{ap_{2}}\left( {{h_{2}\rho_{t}t_{2}} + n_{2}} \right)} - \frac{\omega_{2}\rho_{s}p_{1}}{a}}}}} & (6) \\{{u_{k} = {{u_{k - 1} + {\frac{p_{1}}{a^{k - 1}p_{k}}b_{k}}} = {{p_{1}{\sum\limits_{m = 1}^{k}\frac{b_{m}}{a^{m^{- 1}}p_{m}}}} = {{h_{1}\rho_{t}t_{1}} + n_{1} - {\frac{p_{1}}{a^{k}p_{k + 1}}\left( {{h_{k + 1}\rho_{t}t_{k + 1}} + n_{k + 1}} \right)} - {\rho_{s}p_{1}{\sum\limits_{m = 1}^{k}\frac{\omega_{m + 1}}{a^{m}}}}}}}},\mspace{20mu} {k \in \left\{ {2,L,{L_{1} - 1}} \right\}}} & (7)\end{matrix}$

The estimated results can be obtained below.

$\begin{matrix}{z_{1} = {{\frac{1}{L_{1} - 1}{\sum\limits_{k = 1}^{L_{1} - 1}u_{k}}} = {{h_{1}\rho_{t}t_{1}} + n_{1} + ɛ_{1}}}} & (8) \\{z_{k} = {{\frac{a^{k - 1}p_{k}}{p_{1}}\left( {z_{1} - u_{k - 1}} \right)} = {{h_{k}\rho_{t}t_{k}} + n_{k} + ɛ_{k}}}} & (9)\end{matrix}$

Where ε_(k) in the formula (9) is the residual signal generated duringthe interference cancellation process by the BKIC module, and ε_(k) canbe modeled as a Gaussian distribution. For slow fading, (a→1), thevariance of ε_(k) is small, so the ε_(k) in y_(k) can be removed toobtain the estimated h_(k)ρ_(t)t_(k)+n_(k), that is, theh_(k)ρ_(t)t_(k)+n_(k) estimated in each path is added to each other toobtain the estimated target signal without the pilot signal.

In addition, in step S102, the carrier signal is subjected to BKICprocessing to obtain a target signal, and the target signal is subjectedto differential signal processing to obtain a target authenticationsignal.

In the present embodiment, the method of differential signal processingis described below.

Under the first condition, the expression of differential signalprocessing is described below.

$\begin{matrix}{{{r_{k}H_{1}} = {{\frac{1}{\rho_{t}^{2}}z_{k}z_{k + 1}^{*}} = {{a{h_{k}}^{2}t_{k}t_{k + 1}^{*}} + \Delta_{k}}}},{{iL} \leq k \leq {{iL} + L_{1} - 1}}} & (10)\end{matrix}$

Where Δ_(k) is the residual signal and may be approximately modeled as aGaussian random variable with a mean of zero and a variance of σ_(Δ)_(k) ².

Under the second condition, the expression of the differential signalprocessing is described below.

$\begin{matrix}{{r_{k}H_{0}} = {{\frac{1}{\rho_{t}^{2}}\left( {n_{k} + ɛ_{k}} \right)\left( {n_{k + 1} + ɛ_{k + 1}} \right)^{*}} = \nabla_{k}}} & (11)\end{matrix}$

Where ∇_(k) is a zero-mean complex Gaussian random variable.

In the present embodiment, the physical layer blind authenticationmethod further includes: obtaining, by the receiver, a reference signalbased on the key and the pilot signal, performing differential signalprocessing on the reference signal to obtain a reference authenticationsignal, and calculating the correlation between the targetauthentication signal and the reference authentication signal to obtaina test statistic (step S103)

In step S103, obtaining the reference signal based on the key and thepilot signal refers to obtaining the reference signal based on the keyand the pilot signal using the hash matrix. Thereby, the referencesignal is processed to obtain the reference authentication signal, andwhether the target authentication signal passes the authentication canbe determined according to the correlation between the referenceauthentication signal and the target authentication signal.

In step S103, the reference signal is subjected to differential signalprocessing to obtain the reference authentication signal, and thecorrelation between the target authentication signal and the referenceauthentication signal is calculated to obtain the test statistic, andthe next determination may be performed according to the value of thetest statistic.

In the present embodiment, the reference signal is subjected todifferential signal processing to obtain the reference authenticationsignal. The method of differential signal processing is the same as thedifferential processing method in the above step S102.

In the above step S102, the carrier signal received by the receiver mayinclude an authentication signal, and that the carrier signal includesthe authentication information is set as a first condition, and that thecarrier signal does not include the authentication signal is set as asecond condition.

At the receiver, for the carrier signal, blind known interferencecancellation (BKIC) processing is performed on the carrier signal ineach path of the frequency selective fading channel to obtain a targetsignal, and differential signal processing is performed on the targetsignal to obtain a target authentication signal. At the receiver, areference signal is obtained based on the key and the pilot signal. Thereference signal is subjected to differential (DP) signal processing toobtain a reference authentication signal. The rules for generating thereference signal by the hash matrix, the key and the pilot signal at thereceiver are the same as the rules for generating the authenticationsignal by the hash matrix, the key and the pilot signal at thetransmitter. The reference authentication signal may be regarded as theauthentication signal under the first condition. The targetauthentication signal may be regarded as the carrier signal under thefirst condition. Thus, the first condition may be expressed as includingthe reference authentication signal in the target authentication signal;the second condition may be expressed as not including the referenceauthentication signal in the target authentication signal.

In the present embodiment, the physical layer blind authenticationmethod further includes comparing the test statistic with a prescribedthreshold to determine whether the carrier signal can pass theauthentication (step S104).

In step S104, if the test statistic is not less than the prescribedthreshold, it is determined that the carrier signal passes theauthentication; if the test statistic is less than the prescribedthreshold, it is determined that the carrier signal has not passed theauthentication.

In the present embodiment, if the test statistic is not less than theprescribed threshold, the carrier signal includes the referenceauthentication signal, that is, the carrier signal passes theauthentication; if the test statistic is less than the prescribedthreshold, the carrier signal does not include the referenceauthentication signal, that is, the carrier signal has not passed theauthentication.

In addition, in the present embodiment, the prescribed threshold isobtained by assuming the verification condition, and the first conditionand the second condition described above are the first condition H₁ andthe second condition H₀ of the assumption verification condition,respectively.

In the present embodiment, under the first condition H₁, the expressionof the test statistic is as follows:

$\begin{matrix}{{\tau_{i}H_{1}} = {{d_{i}^{H}r_{i}} = {{a{\sum\limits_{k = 1}^{L_{1} - 1}{{h_{{i\; L} + k}t_{{i\; L} + k}t_{{i\; L} + k + 1}}}^{2}}} + v_{i}}}} & (13)\end{matrix}$

Under the second condition H₀, the expression of the test statistic isas follows:

$\begin{matrix}{{\tau_{i}H_{0}} = {\varphi_{i} = {\sum\limits_{k = 1}^{L_{1} - 1}{t_{k}^{*}t_{k + 1}\nabla_{k}}}}} & (14)\end{matrix}$

Where

$v_{i} = {\sum\limits_{k = 1}^{L_{1} - 1}{t_{k}^{*}t_{k + 1}\Delta_{k}}}$

is a Gaussian random variable with a mean of zero and a variance ofσ_(v) _(i) ²=(L₁−1)σ_(Δ) ²σ_(p) ⁴. ϕ_(i) is a Gaussian random variablewith a mean of zero and a variance of σ_(ϕ) _(i) ²=(L₁−1)σ_(∇) ²σ_(p) ⁴.

In addition, the prescribed threshold τ_(i) ⁰ is determined by the falsealarm probability ε_(FA) associated with the (τ_(i)|H₀) distribution,and is expressed as follows:

$\begin{matrix}{\tau_{i}^{0} = {{\arg {\min\limits_{\tau}{\Phi \left( {\tau \text{/}\sigma_{\varphi_{i}}} \right)}}} \geq {1 - ɛ_{FA}}}} & (15)\end{matrix}$

Where (τ_(i)|H₀) is the test statistic obtained under the secondcondition, that is, the statistical characteristic of the pilot signal.Thus, the prescribed threshold may be obtained based on the statisticalcharacteristic of the pilot signal and the preset upper limit of thefalse alarm probability.

In addition, in the present embodiment, if the identity of thetransmitter is authenticated, the authentication signal may be used asan extra pilot signal to recover the signal. Thereby, the performance ofsignal symbol recovery and the estimation performance of the channelresponse can be improved.

In addition, in the present embodiment, the authentication signal issuperimposed on the pilot signal, avoiding the adverse effect on theextraction of the conventional signal. Thereby, the signal tointerference plus noise ratio (SINR) of the receiver is prevented frombeing reduced.

In the present embodiment, the physical layer blind authenticationmethod of the wireless communication frequency selective fading channelbased on the smoothing technique does not need to occupy extra signalbandwidth. In addition, at the receiver, when the information signal isextracted from the carrier signal, the authentication signal does notbecome the noise of the information signal, that is, the authenticationsignal does not affect the extraction of the information signal. Theauthentication signal does not affect the statistical characteristics ofthe noise at the receiver.

In the present embodiment, the physical layer blind authenticationmethod deals with a frequency selective fading channel with multiplepaths, that is, a multipath channel, and is more suitable for a complexand variable wireless communication environment in an actualcommunication scenario. In addition, the authentication signal issuperimposed on the pilot signal. If the entire signal obtained bysuperimposing the authentication signal and the pilot is used as thepilot signal for channel estimation, the accuracy of the channelestimation can further be improved.

The embodiments disclose a physical layer blind authentication systemfor a wireless communication frequency selective fading channel based ona smoothing technique. FIG. 5 is a schematic diagram illustrating signalprocessing modules of a transmitter in a physical layer blindauthentication system according to an embodiment of the presentdisclosure. FIG. 6 is a schematic diagram illustrating signal processingmodules of a receiver in a physical layer blind authentication systemaccording to an embodiment of the present disclosure.

In the present embodiment, as shown in FIG. 5, the physical layer blindauthentication system includes a transmitting device 20. Thetransmitting device 20 includes a first generation module 201, a secondgeneration module 202, and a synthesizing module 203.

In the present embodiment, as shown in FIG. 5, the first generationmodule 201 generates an authentication signal, that is, the key and thepilot signal generate an authentication signal via the first generationmodule 201. The first generation module 201 includes a hash matrix. Theauthentication signal is obtained based on the key and the pilot signalby using a hash matrix. The obtained authentication signal and the pilotsignal have the same signal length.

In the present embodiment, as shown in FIG. 5, the second generationmodule 202 generates a pilot portion of the carrier signal. That is, theauthentication signal is loaded onto the pilot signal via the secondgeneration module 202 to generate a pilot portion of the carrier signal.The expression of the pilot portion of the carrier signal is formula(1). In addition, the length of the pilot portion of the carrier signalis the signal length of the authentication signal or the signal lengthof the pilot signal.

In the present embodiment, as shown in FIG. 5, the synthesizing module203 generates a carrier signal, that is, the pilot portion and theinformation portion of the carrier signal are combined via thesynthesizing module 203 to generate a carrier signal. The informationportion of the carrier signal is an information signal.

In the present embodiment, the carrier signal is sent in blocksaccording to data blocks, each carrier signal block includes a pilotportion and an information portion, and the sum of the signal length ofthe authentication signal or the pilot signal and the signal length ofthe information signal is equal to the length of each carrier signalblock. In addition, the carrier signal is transmitted in blocks in theform of data blocks to facilitate operation of the data.

In the present embodiment, the carrier signal generated by thetransmitting device 20 at the transmitter reaches the receiving device30 at the receiver via the wireless channel. In addition, the wirelesschannel is a frequency selective fading channel with multiple paths.

In the present embodiment, the physical layer blind authenticationsystem further includes a receiving device 30, and the receiving device30 includes a first processing module, a second processing module, and adetermining module.

In the present embodiment, the first processing module includes a blindknown interference cancellation (BKIC) module 301. The carrier signalpasses through the blind known interference cancellation (BKIC) module301. Specifically, the carrier signal in each path of the frequencyselective fading channel is subjected to blind known interferencecancellation (BKIC) processing in the blind known interferencecancellation (BKIC) module 301, cancelling the pilot signal in thecarrier signal.

In the present embodiment, the blind known interference cancellation(BKIC) module 301 employs the BKIC processing method in step S102 inwhich the adjacent symbols are used to cancel the pilot signal throughthe smoothing technique. The specific steps are as shown in FIG. 4. TheBKIC processing includes determining an expression of each symbol underdifferent conditions (step S401) and estimating the target signal usingthe expression of the symbol (step S402).

In the present embodiment, as shown in FIG. 6, the first processingmodule further includes a differential (DP) processing module 302. TheDP processing module 302 employs the differential signal processingmethod in step S102. The DP processing module 302 performs differentialsignal processing on the target signal to obtain a target authenticationsignal. Thereby, the effect of h_(k) in the target authentication signalis cancelled, i.e., the effect of the channel on the carrier signal iscancelled.

In the DP processing module 302, under the first condition, theexpression of the differential signal processing is formula (10), whereΔ_(k) is the residual signal, which may be approximately modeled as aGaussian random variable with a mean of zero and a variance of σ_(Δ)_(k) ². Under the second condition, the expression of the differentialsignal processing is formula (11), where ∇_(k) is a zero-mean complexGaussian random variable.

In the present embodiment, as shown in FIG. 6, the second processingmodule further includes a hash matrix processing module 303. A referencesignal is obtained based on the pilot signal and the key via the hashmatrix processing module 303. The hash matrix processing module 303employs the method of generating the reference signal in step S103, andthe hash matrix processing module 303 includes a hash matrix.

In the present embodiment, as shown in FIG. 6, the second processingmodule further includes a differential (DP) processing module 304. Thedifferential (DP) processing module 304 performs differential signalprocessing on the reference signal to obtain a reference authenticationsignal. The DP processing module 304 employs the differential signalprocessing method in step S103.

In the present embodiment, as shown in FIG. 6, the second processingmodule further includes an operation module 305. The operation module305 is configured to calculate a test statistic of the targetauthentication signal and the reference authentication signal. Thecalculation method used by the operation module 305 is the calculationmethod in step S103.

In the present embodiment, as shown in FIG. 6, the second processingmodule further includes a determining module 306. The determining module306 determines whether the target authentication signal passes theauthentication by comparing the test statistic with the prescribedthreshold, that is, it is determined whether the carrier signal can passthe authentication.

In the present embodiment, the prescribed threshold in the determiningmodule 306 is obtained based on the statistical characteristics of thepilot signal and the preset upper limit of the false alarm probability.The calculation method of the prescribed threshold is the thresholdcalculation method in step S103.

The embodiments disclose a physical layer blind authentication device 50for a wireless communication frequency selective fading channel based ona smoothing technique. FIG. 7 is a schematic structural diagram of aphysical layer blind authentication device according to an embodiment ofthe present disclosure. In the present embodiment, both the transmitterand the receiver include the authentication device 50 as shown in FIG.7.

In the present embodiment, as shown in FIG. 7, the authentication device50 includes a processor 501 and a memory 502. The processor 501 and thememory 502 are separately connected to the communication bus. The memory502 may be a high speed random access memory (RAM) or a non-volatilememory. It will be understood by those skilled in the art that thestructure of the authentication device 50 shown in FIG. 7 does notconstitute a limitation of the present disclosure. The structure may bea bus-shaped structure or a star-shaped structure, and may also includemore or fewer components than those shown in FIG. 7, or a combination ofsome components, or a different arrangement of components.

The processor 501 is a control center of the authentication device 50,and may be a central processing unit (CPU). The processor 501 connectsvarious parts of the entire authentication device 50 by using variousinterfaces and lines, and runs or executes software programs and/ormodules stored in the memory 502 as well as calls program codes storedin the memory 502 to perform the operations below.

The transmitter transmits carrier signals to the wireless channel, wherea carrier signal includes an authentication signal, a pilot signal andan information signal, the authentication signal is superimposed on thepilot signal, and the wireless channel is a frequency selective fadingchannel (performed by the authentication device 50 at the transmitter)with multiple paths.

The receiver receives the carrier signals, and performs blind knowninterference cancellation (BKIC) processing on the carrier signal ineach path of the frequency selective fading channel to obtain a targetsignal, and performs differential signal processing on the target signalto obtain a target authentication signal, where in the BKIC processing,a pilot signal is cancelled through a smoothing technique by usingadjacent symbols; the receiver obtains a reference signal based on thekey and the pilot signal, performs differential signal processing on thereference signal to obtain a reference authentication signal, andcalculates a correlation between the target authentication signal andthe reference authentication signal to obtain a test statistic; and thetest statistic is compared with a prescribed threshold to determinewhether the carrier signal can pass authentication (performed by theauthentication device 50 at the receiver).

In the present embodiment, the processor 501 of the authenticationdevice 50 at the transmitter further performs the following operation:the carrier signal is transmitted in blocks in the form of data blocks.

In the present embodiment, the processor 501 of the authenticationdevice 50 at the transmitter further performs the following operation:in each block of the carrier signal, the sum of the signal length of thepilot signal and the signal length of the information signal is equal tothe signal length of the carrier signal.

In the present embodiment, the processor 501 of the authenticationdevice 50 at the receiver further performs the following operation: areference signal is obtained based on the key and the pilot signal usinga hash matrix.

In the present embodiment, the processor 501 of the authenticationdevice 50 at the receiver further performs the following operation: ifthe test statistic is not less than a prescribed threshold, the carriersignal passes the authentication.

In the present embodiment, the processor 501 of the authenticationdevice 50 at the receiver further performs the following operation: theprescribed threshold is obtained based on the statistical characteristicof the pilot signal and the preset upper limit of the false alarmprobability.

In the embodiments, it should be understood that the disclosed devicemay be implemented in other ways. For example, the device embodimentsdescribed above are merely illustrative. For example, the division ofthe units is only a logical function division, and another divisionmanner may be provided in actual implementation. For example, multipleunits or components may be combined or integrated into another system,or some features may be omitted or not implemented. In addition, thecoupling or direct coupling or communication connection shown ordiscussed may be an indirect coupling or communication connectionthrough some interfaces, devices or units, and may be electrical or thelike.

The units described as separate components may or may not be physicallyseparated, and the components displayed as units may or may not bephysical units, that is, may be located in one place, or may bedistributed to multiple network units. Some or all of the units may beselected according to actual needs to achieve the purpose of thesolution of an embodiment.

In addition, each functional unit in each embodiment may be integratedinto one processing unit, or each unit may exist physically separately,or two or more units may be integrated into one unit. The aboveintegrated unit may be implemented in the form of hardware or in theform of a software functional unit.

The integrated unit, if implemented in the form of a software functionalunit and sold or used as a standalone product, may be stored in acomputer readable memory. Based on such understanding, the technicalsolution of the present disclosure or the part contributing to theexisting art or all or part of the technical solution may be embodied inthe form of a software product. The computer software product is storedin a memory and includes several instructions for causing a computerdevice (which may be a personal computer, server or network device,etc.) to perform all or part of the steps of the methods described invarious embodiments of the present disclosure. The foregoing memoryincludes: a USB flash disk, a Read-Only Memory (ROM), a Random AccessMemory (RAM), a removable hard disk, a magnetic disk, or an opticaldisk, and the like, which may store program codes.

The embodiments disclose a computer readable storage medium. One ofordinary skill in the art will appreciate that all or part of thevarious steps of the above-described embodiments may be accomplished bya program (instruction) instructing the associated hardware. The program(instruction) may be stored in a computer readable memory (storagemedium), and the memory may include: a flash disk, a read-only memory(ROM), a random access memory (RAM), a magnetic disk or a CD, etc.

Although the present disclosure is described in detail in conjunctionwith the drawings and embodiments, it should be understood that theabove description is not intended to limit the present disclosure in anyform. Those skilled in the art may make variations and changes withoutdeparting from the spirit and scope of the present disclosure, and suchvariations and changes fall within the scope of the present disclosure.

1. A blind authentication method for a frequency selective fadingchannel based on a smoothing technique, being a physical layerauthentication method for wireless communication of a wirelesscommunication system having a transmitter and a receiver and comprising:transmitting, by the transmitter, carrier signals to a wireless channel,wherein each of the carrier signals comprises an authentication signal,a pilot signal, and an information signal, the authentication signal issuperimposed on the pilot signal, and the wireless channel is afrequency selective fading channel having a plurality of paths;receiving, by the receiver, the carrier signals, performing blind knowninterference cancellation (BKIC) processing on a carrier signal in eachof the plurality of paths of the frequency selective fading channel toobtain a target signal, and performing differential signal processing onthe target signal to obtain a target authentication signal, wherein inthe BKIC processing, a pilot signal in the each of the plurality ofpaths is cancelled through the smoothing technique by using adjacentsymbols; obtaining, by the receiver, a reference signal based on a keyand the pilot signal in the each of the plurality of paths, performingthe differential signal processing on the reference signal to obtain areference authentication signal, and calculating a correlation betweenthe target authentication signal and the reference authentication signalto obtain a test statistic; and comparing the test statistic with aprescribed threshold to determine whether the carrier signal in the eachof the plurality of paths is capable of passing authentication.
 2. Theblind authentication method according to claim 1, wherein each of thecarrier signals is transmitted in blocks in a form of data blocks. 3.The blind authentication method according to claim 2, wherein a sum of alength of a pilot signal in each block of the each of the carriersignals and a length of an information signal in the each block of theeach of the carrier signals is equal to a length of the each block ofthe each of carrier signals.
 4. The blind authentication methodaccording to claim 1, wherein the reference signal is obtained based onthe key and the pilot signal in the each of the plurality of paths byusing a hash matrix.
 5. The blind authentication method according toclaim 1, wherein the carrier signal in the each of the plurality ofpaths passes the authentication in a case where the test statistic isnot less than the prescribed threshold.
 6. The blind authenticationmethod according to claim 1, wherein the prescribed threshold isobtained based on a statistical characteristic of the pilot signal inthe each of the plurality of paths and a preset upper limit of a falsealarm probability.
 7. A blind authentication device for a frequencyselective fading channel based on a smoothing technique, wherein themethod comprises: transmitting, by the transmitter, carrier signals to awireless channel, wherein each of the carrier signals comprises anauthentication signal, a pilot signal, and an information signal, theauthentication signal is superimposed on the pilot signal, and thewireless channel is a frequency selective fading channel having aplurality of paths; receiving, by the receiver, the carrier signals,performing blind known interference cancellation (BKIC) processing on acarrier signal in each of the plurality of paths of the frequencyselective fading channel to obtain a target signal, and performingdifferential signal processing on the target signal to obtain a targetauthentication signal, wherein in the BKIC processing, a pilot signal inthe each of the plurality of paths is cancelled through the smoothingtechnique by using adjacent symbols; obtaining, by the receiver, areference signal based on a key and the pilot signal in the each of theplurality of paths, performing the differential signal processing on thereference signal to obtain a reference authentication signal, andcalculating a correlation between the target authentication signal andthe reference authentication signal to obtain a test statistic; andcomparing the test statistic with a prescribed threshold to determinewhether the carrier signal in the each of the plurality of paths iscapable of passing authentication.
 8. A non-transitory computer readablestorage medium, which is configured to store at least one instructionwhich, when executed by a processor, implements the blind authenticationmethod according to claim
 1. 9. A blind authentication system for afrequency selective fading channel based on a smoothing technique,comprising a transmitting device and a receiving device; wherein thetransmitting device is configured to transmit carrier signals to awireless channel, each of the carrier signals comprises anauthentication signal, a pilot signal and an information signal, theauthentication signal is superimposed on the pilot signal, and thewireless channel is a frequency selective fading channel having aplurality of paths; and wherein the receiving device comprises: a firstprocessing module configured to receive the carrier signals, performblind known interference cancellation (BKIC) processing on a carriersignal in each of the plurality of paths of the frequency selectivefading channel to obtain a target signal, and perform differentialsignal processing on the target signal to obtain a target authenticationsignal, wherein in the BKIC processing, a pilot signal in the each ofthe plurality of paths is cancelled through the smoothing technique byusing adjacent symbols; a second processing module configured to obtaina reference signal based on a key and the pilot signal in the each ofthe plurality of paths, perform the differential signal processing onthe reference signal to obtain a reference authentication signal, andcalculate a correlation between the target authentication signal and thereference authentication signal subjected to the differential signalprocessing to obtain a test statistic; and a determining moduleconfigured to compare the test statistic with a prescribed threshold todetermine whether the carrier signal in the each of the plurality ofpaths is capable of passing authentication.
 10. The blind authenticationsystem according to claim 9, wherein the second processing module isconfigured to obtain the reference signal based on the key and the pilotsignal in the each of the plurality of paths by using a hash matrix. 11.The blind authentication system according to claim 9, wherein in thedetermining module, the prescribed threshold is obtained based on astatistical characteristic of the pilot signal in the each of theplurality of paths and a preset upper limit of a false alarmprobability.